.header,
.video,
#page-main {
    width: 100%;
    img {
        width: 100%;
    }
    video {
        width: 100%;
    }
}

.header {
    position: relative;
    .qr-code {
        width: 25%;
        position: absolute;
        bottom: 4%;
        // width: 2rem;
        // height: 2rem;
        left: 50%;
        transform: translateX(-50%);
    }
}